1. Field of the Invention
The present invention relates to a toner conveying path forming member used for an image forming apparatus such as a copying machine, a printer, a facsimile machine, and an MFP, a toner replenishment unit including the toner conveying path forming member, and an image forming apparatus including the toner replenishment unit.
2. Description of the Related Art
In the related art, an image forming apparatus including a toner replenishment unit that supplies toner to a developing unit has been known. The developing unit visualizes, by using the toner, latent images formed on the surface of photosensitive drums or the like serving as latent image carriers into toner images. Some of such toner replenishment units have a toner conveying device and a toner housing container or the like.
As for the toner conveying device, such a toner conveying device has been known including, for example, a receiving unit that receives toner from the toner housing container, a delivery unit that delivers the toner to the developing unit, and a hollow circular pipeline unit that guides the toner from the receiving unit to the delivery unit. The receiving unit, the delivery unit, and the pipeline unit respectively function as the toner conveying path forming member forming a toner conveying path.
As for the toner housing container, a toner bottle composed of a tubular cylindrical member having a hollow has been known, for example. In the toner bottle, the toner is discharged from an outlet of the toner bottle provided on the side face of an end of the toner bottle. The toner housing container itself may function as the toner conveying path forming member forming the toner conveying path.
In response to a demand for downsizing the image forming apparatus, there are more image forming apparatuses in which a toner conveying member having elasticity is arranged as the toner conveying unit in the pipeline unit of the toner conveying device or inside the toner housing container that functions as the toner conveying path forming member.
By providing an elastic toner conveying member, for example, inside the pipeline unit, the stable toner conveyance ability can be ensured even if a curved portion, where the center line of the pipeline unit that passes through the center of the hollow section perpendicular to the toner conveying direction is curved, is provided. As described above, by providing the curved portion inside the pipeline unit while ensuring the toner conveyance ability, the layout flexibility of the toner replenishment unit in the apparatus is increased compared to the structure in which only the effect of gravity is utilized, and a layout capable of downsizing the main body of the image forming apparatus is also available.
By arranging the toner conveying member having elasticity inside the toner housing container, the stable toner conveyance ability and toner agitating ability can be ensured even with the structure in which the center line passing through the center of the hollow section perpendicular to the toner conveying direction of the toner housing container is arranged substantially horizontal and the height of the main body of the image forming apparatus is shortened. As described above, by arranging the center line of the toner housing container substantially horizontal, while ensuring the toner conveyance ability and toner agitating ability, the main body of the image forming apparatus can also be downsized compared to the structure in which only the effect of gravity is utilized.
However, with the structure in which the elastic toner conveying member is arranged in the toner conveying path forming member, a part of the inner wall of the toner conveying path forming member may be pressed by the toner conveying member directly or via the toner. If the inner wall is pressed as described above, a part of the toner that is being conveyed may be sandwiched at a sandwich field formed between the toner conveying member and the inner wall surface of the toner conveying path forming member and undergoes pressure, thereby generating aggregated toner particles.
If the aggregated toner particles generated in the sandwich field is supplied to the developing unit, without being broken down in the toner conveying path, the defective images are generated as follows, for example. The aggregated toner particles are caught by a member for limiting a developer layer thickness of the developing unit, to cause the developer layer on a developing roller serving as a developer carrier to become uneven, thereby generating defective images such as a white vertical line on the image.
In the related art, the following method has been known as a method for suppressing the generation of the aggregated toner particles in the toner conveying path forming member. In the method, a degree of aggregation serving as one of characteristic values of toner to be used is regulated by two types of mesh opening of a sieve (sieve oscillation measurement method) (Japanese Patent No. 4462492). However, the characteristic values of toner are likely to be influenced by use environment such as temperature and humidity for the image forming apparatus. Accordingly, the characteristic values of the toner cannot be controlled depending on the use environment, whereby sometimes the generation of the aggregated toner particles in the toner conveying path forming member cannot be suppressed.
Therefore, there is a need for a toner conveying path forming member that is hardly influenced by use environment and is capable of suppressing the generation of aggregated toner particles that can cause defective images, even when a part of the inner wall of the toner conveying path forming member is pressed by an elastic toner conveying member provided in a toner conveying path.